This invention relates to electronic devices and more specifically relates to a package for electronic devices having improved cooling.
Semiconductor die such as diodes, transistors, thyristors and the like are usually mounted within a protective housing, frequently a plastic molded structured which encloses the die. The protective packages are made of electrical insulation materials which reduce the ability to remove heat generated by the die over its full surface area and from localized hot spots on the die.
It would be desirable to provide a semiconductor device package which provides excellent electrical insulation properties for the die while providing improved cooling of the die and reducing hot spot heating on the die.
In accordance with the present invention a heat-generating electronic device is suspended in an electrically insulative heat transfer fluid, which is sealed in a housing. The lead frame terminals are sealed in and passed through the housing wall for external connection. At least a portion of the housing is thermally conductive and in direct contact with the electrically insulative heat transfer fluid, which is sealed in the interior volume within the housing. An insulative heat transfer fluid such as any of the well known liquids, for example, GALDEN(copyright) PFPE0001, a perfluoropolyether, which has the chemical formula shown in FIG. 7, then fills at least a portion of the interior of the housing and is in contact with an exposed surface of one or more of the die of the heat generating electronic device. Thus heat produced by the device is carried by conduction and convection through the fluid (preferably a liquid) to the thermally conductive plate or plates, and then to the ambient exterior of the package.
Herein the term thermally conductive is defined as having a coefficient of thermal conductivity of at least 170 W/m K, the thermoconductivity of aluminum nitride. Some other examples of thermally conductive materials are aluminum and alloys of aluminum that are thermally conductive (about 200 W/m K), beryllium oxide (260 W/m K), and copper (393 W/m K), for example.